Terrebonne mulling sediment pipeline

Sunday

Jun 30, 2013 at 12:03 AM

As open water continues to encroach upon Terrebonne's wetlands, contractors for the parish will soon begin to study a new solution.

Xerxes Wilson Staff Writer

As open water continues to encroach upon Terrebonne's wetlands, contractors for the parish will soon begin to study a new solution. The parish are planning a study into the cost and feasibility of building a pipeline from the Atchafalaya River to carry sediment to the parish's starving wetlands.Parish officials stressed that the project is a long way from becoming reality, but say it could be a way to rejuvenate withering wetlands and stave off intrusion of salt water.Parish President Michel Claudet said the idea for the pipeline has been around for some time, and he hopes this study will show the concept is feasible and the cost reasonable. The study is two-pronged. Baton Rouge engineering firm Moffatt & Nichol will study potential sources of sediment along the Atchafalaya, Terrebonne Coastal Restoration Director Nic Matherne said The U.S. Army Corps of Engineers regularly dredge various spots in the river that could serve as a source for the sediment, he said. A sediment trap which could be mined is also a possibility, he added. “The benefit of introducing sediment into the system via pipeline is tapping into a renewable source of sediment in the river,” Matherne said.The second approach looks at potential paths for the 40-50 mile pipeline. That portion of the study will be conducted by Houma-based CB&I. Matherne said the parish has had informal discussions about a partnership that would run the new pipeline along an existing industrial pipeline.Much of the time and cost of such a project comes from permits and building a corridor for the pipe will pass through. Matherne said being able to partner with an existing corridor would greatly reduce harm to wetlands and speed the process. The project is similar to a state project which will carry sediment via pipeline from the Mississippi River west to the Barataria Basin. That project is shorter than the goal for Terrebonne and will cost the state $70 million to $100 million. The pipeline from the Mississippi was originally set to stretch west to the Cloverly area of Lafourche Parish, but was scaled back due to cost. State officials say the intent is to bring the project to Lafourche, but more money is required.Though Terrebonne's concept would require a longer pipeline, Matherne said the cost could be comparable depending on the study results. He said the Mississippi River pipeline requires the construction of a ridge for the corridor. Terrebonne's project could avoid such costs by tying into an existing pipeline's corridor, he said.“The ultimate hope is that we could reach it all the way to eastern Terrebonne,” Matherne said. “We understand that is a very large and bold project that will take a great deal of planning and cooperation.”Matherne said pipelines are advantageous because they can be extended to restore multiple sites, nothing areas near Falgout Canal and the rim of Terrebonne Bay as spots in desperate need. Because the line can be extended, the project would likely take place in phases allowing the parish to pull money from different sources over time. “Once the corridor is in place, we could possibly ask for a few more million to move it further east and keep building on the footprint as we move to different areas in dire need,” Matherne said. Parish government and Terrebonne's Levee District are paying up to $750,000 for the study. That amount will be matched by federal Coastal Impact Assistance.“It's something we feel is important enough not to sit around and wait for it to be a priority for others,” Matherne said. “We want to put some skin in the game to get it prioritized.” Parish officials say they hope taking the lead on the project will ease the way for state and federal coastal restoration money to help pay for the project, especially with billions in BP fines earmarked for coastal restoration projects. “We have this great Morganza (levee) plan, but the hope is that water or surge would never impact that (levee) alignment because we would have enough defense that would knock down storm surge so those levees are not our first line of defense but our last resort,” Matherne said. Once initiated, the study will take about eight months to complete.

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